Encapsulation is used to protect the core materials, such as flavor oil, oleoresin, spice, chemicals and colorants in food processing operations. The technologies generally employed are coating, spray drying, extrusion and coacervation. Finished products are normally in the solid form and can be different in mesh size. The applications of encapsulated materials in food industry are, however, limited to only specific areas. Some examples are encapsulated vitamins and minerals. Incorporating dry encapsulated products in food products often produce uneven distribution of core materials. The high cost normally associated with the encapsulation process also limits the usage of encapsulated products in the food industry.
Spice, oleoresin, flavor oil, color or chemicals are typically added during food processing to produce the desirable flavors, taste and appearance. Oleoresin and flavor oil are coated on carriers, such as salt and dextrose, and mixed with other dry food ingredients before they are used for food production. Because of the exposure of these additives to light and oxygen, the carrier coated oleoresin and flavor oils which are susceptible to oxidation often lose the desired flavor value very quickly. Oleoresin and flavor oils can be added directly into the food production, however, distribution uniformly in the food system is very difficult. This is because of the hydrophobic nature of oleoresin and flavor oil. Several oleoresin and spice producers have used surfactants and emulsifiers to facilitate the distribution of the oleoresin. These approaches have not been effective because the surfactant added in the emulsion system of oleoresin may not be adequate for proper distribution when they are used in different food systems. Therefore, most food manufacturers coat the oleoresin and flavor oils on carriers before they are used. This can limit the shelf life of the oleoresin and flavor oil, and pose the significant problem in production scheduling.
Oleoresin and flavors are encapsulated by various technologies. Two recent inventions are used as examples to demonstrate the state of the art. Heat-stable and fracturable, spray-dried, free-flowing flavor oil capsules having a coating of gelatin, carboxymethyl cellulose, gum arabic, casein and alginate, and mixture of the above are described in WO 93/19622. This publication describes the art of crosslinking of gelatin with dialdehyde compounds to form a complete coating envelope for the core materials. The core materials are protected throughout the food processing. Core materials are released when coating materials are fractured by physical force, e.g., when the product is consumed.
In published European patent applications EP 455598 and EP 401954, flavor oils have been encapsulated in the form of coacervated microcapsules, which comprise a core of flavor oil and a coating layer around the core. The coating layer is prepared by coacervation which is a process for the aggregation of colloidal spheres held together by electrostatic forces. In complex coacervation, the aggregation of colloidal spheres is a mixture of two or more oppositely charged hydrophilic colloidal materials of both cationic and anionic types. Coacervation to uniformly distribute the colloidal materials around the flavor oil droplets, is then carried out by diluting an emulsion of the flavor oil in the presence of such colloidal materials with water, adjusting the pH of the emulsion or the temperature, or by any combination of such techniques.
Spice and food ingredients are added in dry form into the raw food ingredients during normal processing. The addition of dry ingredients in the process is time consuming and labor intensive. This poses the problem of continuous operation in the industry, especially for the small or medium size companies. Spice manufacturers have attempted to convert the dry spice operation into liquid spice. However, it is not successful because the phase separation and sedimentation of some of the spices occurred when spice is mixed with the water.
While many improvements have been made in the encapsulation and liquid spice production, further improvements are needed to reduce the costs of production of the encapsulation process. Also, uniformly distributed spices in the liquid medium would be beneficial for the food manufacturers. These improvements would make continuous manufacturing processes possible for products that need dry spices or the described ingredients in the formulation.